Vehicles such as automobiles, trucks, and aircrafts may include multiple electronic modules for monitoring and controlling systems such as engines, exhaust emission systems, and ergonomic control systems. As an example, an automobile may include an electronic control module to receive engine performance information from an engine performance module, provide performance information to a user via a user interface module, and provide control commands to the engine performance module to control engine performance. Wiring a vehicle to interconnect the multiple electronic modules to each other may be complex and costly. For example, in vehicles with limited space, wiring the vehicle may add complexity to the design of the vehicle and of electronic modules therein, and may also add cost to the vehicle assembly process. Further, such wiring may complicate replacing or adding electronic modules in the vehicle.
Communication standards that define communication networks for interconnecting electronic modules within a vehicle have been developed to reduce problems associated with wiring vehicles. Such communication networks generally allow multiple electronic modules to share a communication medium, or bus, and communicate among themselves through the shared bus. One such communication network is provided by the controller area network (CAN) bus standard (International Standards Organization (ISO) 11898), designed originally for use within automobiles but commonly used in a wide variety of applications, including industrial automation, heavy machinery, and military vehicles.
FIG. 1 illustrates a CAN bus network 10 as an example of a communication network for interconnecting electronic modules within a vehicle. The CAN bus network 10 includes a CAN bus 12 and a plurality of electronic modules 14(1)-14(N) (generally, electronic modules 14) interconnected through the CAN bus 12. The electronic modules 14 may include engine control modules, exhaust emission control modules, and ergonomic control modules, for example. The CAN bus 12 includes data lines 16 and 18 for transmitting a differential signal that carries data between the electronic modules 14. The CAN bus network 10 further includes bus connectors 20(1)-20(N) (generally, bus connectors 20), configured to provide a communication path between the electronic modules 14 and the CAN bus 12. In particular, the bus connectors 20 include data lines 22(1)-22(N) and 24(1)-24(N) for electrically coupling a corresponding electronic module 14 to the data lines 16 and 18 of the CAN bus 12, respectively. Accordingly, each of the electronic modules 14 can communicate with each of the other electronic modules 14 through the CAN bus 12 instead of being wired to each of the other electronic modules 14 separately.
Safety considerations may require that such networks provide a high level of reliability in terms of message delivery assurance and physical protection against external elements. For example, in certain environments, electromagnetic interference (EMI) may affect the performance of a network by affecting the voltage/current levels of the network's transmission medium. Therefore, protection against EMI may be necessary to maintain reliable data communications. Accordingly, communication network standards may require or recommend specific ways to protect a corresponding communication medium against EMI. For example, section J1939/11 of the CAN bus standard requires protection against EMI, whereas section J1939/15 of the CAN bus standard does not.
FIG. 2 illustrates a bus connector 26 for connecting an electronic module 14 to the CAN bus 12 illustrated in FIG. 1 according to section J1939/11 of the CAN bus standard. FIG. 2 will be discussed in conjunction with FIG. 1. The bus connector 26 includes data lines 28 and 30 for connecting an electronic module 14 to the data lines 16 and 18 of the CAN bus 12, respectively. The bus connector 26 further includes an EMI shield 32 for protecting a differential signal carried from the CAN bus 12 from EMI, as required by section J1939/11 of the CAN bus standard. The bus connector 26 further includes EMI shield lines 34A and 34B (generally, EMI shield lines 34) electrically coupled to the EMI shield 32 for discharging an electric charge accumulated at the EMI shield 32. This allows for the electric charge to be discharged into, for example, one or more of the electronic modules 14, thus protecting the differential signal carried by data lines 28 and 30 from EMI.
However, the electronic modules 14 may not be configured to receive or “digest” the EMI shield lines 34 of the bus connector 26 and discharge the electric charge in the EMI shield lines 34. For example, an interface of the electronic module 14(1) (FIG. 1) may not support section J1939/11 of the CAN bus standard, and therefore, may not include a contact line for digesting the EMI shield lines 34 from the bus connector 26 and discharge the electric charge in the EMI shield lines 34. Accordingly, connecting the electronic module 14(1) to the CAN bus 12 using the bus connector 26 leaves the EMI shield lines 34 unterminated on the corresponding end of the bus connector 26. This leaves a corresponding EMI charge in the EMI shield 32 and the corresponding differential signal unprotected from EMI, thus decreasing reliability of communications therein.